why wont my dogs hunt for someone else?

Every body has had it happen . I sold a dog to a friend for a grand that was ajam up silent strike dog every dog in his yard was his kin and came from me. The dog did not eat for a week and walked by truck every hunt that week even though he had hunted a hundred times with this guy and was raised with his pack. I went to get him bought barbacoa taco on way gave it to him and he hunted his butt off all weekend. I kept him till he got kilt he turned out to be one of the best dogs i have ever raised , so even though he cost me a grand when i needed it i would not have taken 5 grand for him the night he died. I miss him on every hunt. "RIP HUD" . If he is just a help dog i would not worry about it they are like bull dogs they are a dime a dozen not to be mean but i have never and will never keep a help dog in my pack period!! .